docs: def _add_qualified_edge(self, u, v, relation, annotations, subject_modifier, object_modifier) -> str:
          """Add an edge, then adds the opposite direction edge if it should."""
          sha512 = self._add_qualified_edge_helper(
              u,
              v,
              relation=relation,
              annotations=annotations,
              subject_modifier=subject_modifier,
              object_modifier=object_modifier,
          )
  
          if relation in TWO_WAY_RELATIONS:
              self._add_qualified_edge_helper(
                  v,
                  u,
                  relation=relation,
                  annotations=annotations,
                  object_modifier=subject_modifier,
                  subject_modifier=object_modifier,
              )
  
          return sha512